From 1913 to 1951, Dr. Leo Stanley, chief surgeon at the San Quentin Prison, performed a wide variety of experiments on hundreds of prisoners at San Quentin. Many of the experiments involved testicular implants, where Stanley would take the testicles out of executed prisoners and surgically implant them into living prisoners. In other experiments, he attempted to implant the testicles of rams, goats, and boars into living prisoners. Stanley also performed various eugenics experiments, and forced sterilizations on San Quentin prisoners.[8] Stanley believed that his experiments would rejuvenate old men, control crime (which he believed had biological causes), and prevent the "unfit" from reproducing wrote: